The present invention relates generally to refrigerators and more particularly to a forced air cooling arrangement for the machinery compartment of a refrigerator.
In many modern refrigerators a motor-compressor and a condenser are mounted in a machinery compartment at the bottom of a cabinet and a fan is provided for circulating air through the compartment. The primary concern with respect to the air flow through the compartment has been directed to moving a high volume of air over the condenser and to also move a portion of the air over the motor-compressor to transfer heat during operation. In the usual arrangement, the machinery compartment is divided into two side-by-side sections by means of a longitudinally extending partition running generally from the front of the compartment to the rear wall and having a fan mounted in the rear portion of the partition. A motor-compressor unit and a condenser are mounted in one section of the compartment and a defrost water drain pan is positioned in the other section of the compartment. The fan draws a stream of air inwardly through a front opening in one section over the condenser and compressor and discharges the air into the other section over the drain pan and primarily out the front of this section of the compartment. With this arrangement the volume of air flow over the compressor is reduced due to the restrictions and diffusion of air flow imposed by the condenser. Further, the air-borne grease, lint and dust particles picked up in the air which are drawn into the machinery compartment eventually block the upstream face of the condenser and further reduce the air flow which reaches the compressor. The clogging of the condenser results in both an excessive rise in condenser temperature and reduced flow over the compressor, producing elevated compressor temperatures.
Another arrangement is shown in U.S. Pat. No. 3,785,168 to Domingorene, having a transverse fan which draws air across a condenser then over a portion of the motor-compressor with the discharge of the fan directing air out of an outlet. Another machinery compartment arrangement as shown in U.S. Pat. No. 1,281,027 to Kramer discloses a vertical coiled condenser, a compressor and an axial fan in series. The fan draws air across the condenser and then across a compressor, with the discharge of the fan directed to an air outlet.
The condenser used in the above-described cooling arrangement usually comprise a stack of coiled or serpentine refrigerant tubing provided with a plurality of closely spaced wire or plate-type fins. The serpentine tubing is folded to form two or more superimposed sections or tiers in order to provide the required heat transfer surface within the volume provided by the machinery compartment. As previously discussed, a problem with such forced air machinery compartments has been the accumulation of dust and other foreign substances on the condenser which acts as insulation and materially lowers the condenser efficiency. The coiled condensers and the multi-layered condenser arrangements tend to restrict the flow of air over the condenser and tend to provide traps which clog with the dust and other foreign particles. This dust further restricts air flow and requires that the condensers must periodically be cleaned.
An arrangement shown in U.S. Pat. No. 3,736,768 to Harbour et al recognizes that performance could be improved by directing air directly against the motor-compressor unit. Although the patent to Harbour et al discusses air flow against what is referred to as a compressor, the usual motor-compressor unit (item 24 of Harbour et al) is shown with no indication where the compressor portion of the motor-compressor is located relative to the air flow. Aside from Harbour et al's failure to recognize that performance could be improved by positioning the compressor portion of the motor-compressor unit adjacent the fan so as to be directly subjected to air discharged by the fan, Harbour et al disclose no cooling arrangement which optimizes the shape and position of the condenser and the air flow through the machinery compartment to maximize performance while minimizing manufacturing costs.
Accordingly, one object of the present invention is to provide an arrangement for air flow through the machinery compartment which improves removal of heat from the compressor.
Another object of the invention is to provide a cooling arrangement for a machinery compartment of a refrigerator which cooling arrangement reduces collection of dust on the condenser and essentially eliminates any requirement for cleaning the condenser during the life of the refrigerator.
Another object is to provide an arrangement for air flow through the machinery compartment which permits a reduction of condenser size with no loss of refrigeration performance.
Another object is to make use of a drain pan for the additional purpose of causing more effective air flow over the condenser.
Still a further object of the present invention is to provide a cooling arrangement for a machinery compartment which permits a low profile of the refrigerator cabinet.